Water supplementation enhances the effect of high-fiber diet on stool frequency and laxative consumption in adult patients with functional constipation

Hepatogastroenterology. 1998 May-Jun;45(21):727-32.


Background/aims: The purpose of this study was to determine the effects of a high-fiber diet and fluid supplementation in patients with functional chronic constipation.

Methodology: One hundred and seventeen patients with chronic functional constipation (aged 18-50 years) were randomly divided into two treatment groups. For two months both groups consumed a standard diet providing approximately 25 g fiber per day. Group 1 (58 patients) was allowed ad libitum fluid intake, while Group 2 was instructed to drink 2 liters of mineral water per day. Compliance was monitored throughout the study and results were assessed in terms of bowel-movement frequency and laxative use.

Results: Fiber intake was similar in the two groups, while total daily fluid intake in Group 2 (mean 2.1 liters) was significantly greater than that of Group 1 (1.1 liters)(p < 0.001). In both groups, there were statistically significant increases in stool frequency and decreases in laxative use during the two-month trial, but both changes were greater in Group 2 (stool frequency: p < 0.001 vs. Group 1; laxative use: p < 0.001 vs Group 1).

Conclusions: A daily fiber intake of 25 g can increase stool frequency in patients with chronic functional constipation, and this effect can be significantly enhanced by increasing fluid intake to 1.5-2.0 liters/day.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Cathartics / therapeutic use*
  • Constipation / therapy*
  • Dietary Fiber / therapeutic use*
  • Drinking*
  • Humans
  • Middle Aged


  • Cathartics
  • Dietary Fiber